نتایج جستجو برای: fourier
تعداد نتایج: 61536 فیلتر نتایج به سال:
Grazing X-ray reflectometry allows the analysis of thin layer stacks. The fitting of the reflectivity curve by a trial and error method can be used in order to determine the parameters of the films. Fourier analysis of the experimental reflectivity can directly give a rough determination of the profit index. Application to real examples shows the validity of the method.
The Truncated Fourier Transform (tft) is a variation of the Discrete Fourier Transform (dft/fft) that allows for input vectors that do not have length 2 n for n a positive integer. We present the univariate version of the tft, originally due to Joris van der Hoeven, heavily illustrating the presentation in order to make these methods accessible to a broader audience.
We test various features for recognition of leaves of wooden species. We compare Fourier descriptors, Zernike moments, Legendre moments and Chebyshev moments. All the features are computed from the leaf boundary only. Experimental evaluation on real data indicates that Fourier descriptors slightly outperform the other tested features.
Fourier transforms, integer and fractional, are ubiquitous mathematical tools in basic and applied science. Certainly, since the ordinary Fourier transform is merely a particular case of a continuous set of fractional Fourier domains, every property and application of the ordinary Fourier transform becomes a special case of the fractional Fourier transform. Despite the great practical importanc...
We give a detailed study of the discrete Fourier transform (DFT) of r-even arithmetic functions, which form a subspace of the space of r-periodic arithmetic functions. We consider the DFT of sequences of r-even functions, their mean values and Dirichlet series. Our results generalize properties of the Ramanujan sum. We show that some known properties of r-even functions and of the Ramanujan sum...
This paper introduces the concept of Fourier knot. A Fourier knot is a knot that is represented by a parametrized curve in three dimensional space such that the three coordinate functions of the curve are each finite Fourier series in the parameter. That is, the knot can be regarded as the result of independent vibrations in each of the coordinate directions with each of these vibrations being ...
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